//
//  Book.m
//  InstanceDemo
//
//  Created by fangyuan ding on 2020/10/27.
//  Copyright © 2020 fangyuan ding. All rights reserved.
//

#import "Book.h"

@implementation Book

static Book *_sharedClient = nil;
//获取单例
+ (instancetype)instance{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedClient = [[[self class] alloc] init];
    });
    return _sharedClient;
}
//打印文本
+ (void)print:(NSString *)msg{
    
}
@end
